Chagigah, Chapter 3, Mishnah 5. In the previous mishnah we dealt with the purity of jugs and barrels and with the reliability of amei ha'aretz regarding their own barrels. Our mishnah continues and establishes a boundary within which an am ha'aretz is believed regarding the purity of earthenware vessels.
The great need for earthenware vessels in Jerusalem:
In Jerusalem there was a great need for large numbers of earthenware vessels, since the sacrificial meat was cooked in them, and once the time for eating it had passed the vessels had to be broken because of nosar: the absorbed flavor that the earthenware vessels took in from the offerings must be destroyed once the time for eating has passed. Hence the need for a large supply of earthenware vessels.
On the other hand, the kilns in which the vessels were produced were not set up inside Jerusalem, because of the air pollution, so the manufacture of earthenware vessels took place outside the city. The mishnah therefore establishes a dividing line outside Jerusalem, within which an am ha'aretz is believed regarding the purity of the barrels for the purposes of sacrificial food.
The wording of the mishnah:
"Min haModi'im ulifnim ne'emanin al klei cheres" - Modi'im is a place located fifteen mil from Jerusalem. Throughout the entire area from there inward toward Jerusalem, amei ha'aretz are believed regarding earthenware vessels when they say that they are pure. This reliability was granted for the needs of sacrificial food alone and not for the needs of Terumah, since it was specifically with regard to sacrificial food that there was a special need for many vessels to be readily available.
"Min haModi'im ulachutz ein ne'emanin" - from Modi'im outward, beyond this boundary, amei ha'aretz are no longer believed.
And how does this play out in practice?
"HaKadar shehu mocher hakedeirot, nichnas lifnim min haModi'im" - the potter, that is, the manufacturer of earthenware vessels who sells his pots, who enters within the boundary of Modi'im. And this includes:
"Hu haKadar" - the manufacturer himself.
"Vehen hakedeirot" - those same barrels in his possession.
"Vehen halokchin" - those same buyers.
"Ne'eman" - as long as they are within the boundaries, they are all believed. "Yatza - eino ne'eman" - once they have gone outside Modi'im, their reliability no longer applies.
In summary: in this mishnah we learned that because of the great need for earthenware vessels in Jerusalem for cooking sacrificial food and breaking the vessels because of nosar, and because the vessels were manufactured outside the city, the area of Modi'im was set as a dividing line: from Modi'im inward amei ha'aretz are believed regarding the purity of earthenware vessels for the purposes of sacrificial food alone, and from Modi'im outward there is no reliability - not for the potter, not for the pots and not for the buyers.